Alternating current solenoid



United States Patent 3,166,692 ALTERNATING CURRENT SOLENOID Robert E. Forrester and Alan H. Cornish, Corry, Pa., assignors to Aero-Flow Dynamics, Inc., Corry, Pa., a corporation of New York Filed Sept. 25, 1961, Ser. No. 140,277

2 Claims. (Cl. 317186) I This invention relates to solenoid structures generally and more particularly to an improved A.C. solenoid especially adapted to provide effective operation in environments where high pressures may be experienced.

It has long been advantageous to utilize solenoid actuators to control the operation of valve units in a high pressure fluid system, for the control capabilities of solenoid valve actuators render them desirable for use in aircraft systems, fuel control systems, and similar high pressure hydraulic systems. However, solenoid actuators previously developed for use in high pressure fluid or hydraulic systems have been subject to numerous disadvantages occasioned by the constructional features required to enable the solenoids to withstand the extreme pressures to which they would be submitted.

The primary disadvantages experienced by previously developed A.C. solenoid valve actuators has been the large current losses incurred through the use of an internal tube or housing which isolatesthe electrical components of the solenoid from the solenoid core structure and movable plunger. in high frequency solenoid'structures, as the'current loss is a direct function of frequencyl, The internal housing or tube is subjected tothe'high fluid pressures experienced by the valve or similar component to which the solenoid is attached, and, therefore, this internal housing has previously included a thick-walled tube of high strength metal lic material. The inner housing interferes with-the magnetic flux path within the solenoid, thereby causing high magnetic and eddy current losses which detract from the ovei-all efliciency of the solenoid. It, has been established, that'the wattage consumed by a'v'al've actuatingsolenoid is a direct function of the thickness of thislinner housing. f

"It is the primary object qfuii invention to provide an improved solenoidcapable; of efl icient operationin a high pressure environment.

Another-object of this invention is to provide an imj-f proved solenoidespecially adapted for use as an actuator for valve units or similar components included within a'high pressure fluid' system. I I

A further, object of this invention'ist'o provide'an img proved solenoid" having constructional characteristics which insure eflicient operation in a high pressureenviron- I V ment with minimum magnetic and'eddyjcurrentlosses.

- Another object of t his invention is to? provide an im'-' proved solenoid actuator capable of withstariding theex-. treme pressures inherent'influid pressure systems while incorporating a thin-walledfinner housing assemblyto iso late the electrical componentsof thejsolenoid fronrthe" solenoid plunger unit.

A further object of this proved solenoid having 'a thin-walledinnerhousing assembly sectionally constructed from materials having dif fering'r'nagnetic properties to minimize nagnetic and-eddy current losses which is made, capable of withstanding internal pressures by theprovision of a strong surrounding. field and coil assembly which receives substantially all of the pressure ,fro'mthe inner housing economical solenoid of reduced size and weight which is These losses are especially prevalent invention isfto provide an inipended claims, certain details of construction of which are illustrated in the accompanying drawings in which:

FIGURE 1 is a view in side elevation of the solenoid of the present invention,

FIGURE 2 is an elevational view of the left-hand end of the solenoid of FIGURE 1, and

FIGURE 3 is an enlarged, longitudinal sectional view of the solenoid of the present invention taken along lines 3-3 of FIGURE 2.

Referring now to FIGURES l and 2, the-solenoid of the present invention indicated generally at 10 includes a hollow, body member 11 having an open end about which a flange 12 is provided. Flange 12 includes a plurality of apertures 13 through which suitable attaching means (not shown) may be inserted to secure the solenoid 10 to a high pressure valve or other similar device.

Projecting from the interior of the body 11 is an actuating pin 14 which extends through a slotted core member 15 to be hereafter described.

A pair of terminal posts 16 extend from theclosed end of the solenoid body 11 opposite the flange 12, and are adapted to be electrically connected to a suitable power source.

Referring now to FIGURE 3, it may be seen that flange 12 is provided with a circular cut-away section 17 which receives a circular shoulder 18 of an inner cylindrical housing assembly 19.- The sidewalls of the housing 19 are formed by three cylindrical, ring-like sections 20, 21 and '22 which are connected by welding to form a solid cylindrical wall 23. The individual sections of wall 23 are composed of magnetic and nonmagnetic material'with end section 20, which includes the shoulder18, and end section 22 being of magnetic material, while middle section 21 is formed from nonmagnetic material. Sections 20, 21 and 22 are machined to such an extent that the resulting wall 23 is as thin as possible. -Itjhas b'een found feasible, where the inner assembly-19 of the solenoid '10 isrequi'r'ed to contain a pressure of 10,000 psi, to machine the wall 23 to a thickness of only .016 inch. 3

means. r

. The shoulder 18 ofthe inner housing assembly 19 is provided with a circularrcut-out portion 25 which seats a shoulder 26, formed at one end of the stationary core -15. Core 15 is encased withinv the inner housing 19 and includes an axially extending bore 27 through which the actuating pin .14 of the solenoid 10' projects. Actu-- ating pin 14 is connected to a'solenoid plunger 28, which is-enca'sed within theinner housing assembly 19 in spaced relationship to the-core member 15.. Both the core member '15 and the plunger 28 are provided'with narrow slots 41 extending lengthwise thereofaas indicated by FIGURE 2. I 4

The wall 23 of the -internal housing assembly '19 is spaced from the body member-11 to provide a chamber wherein the field and coilassembly 29 of'the. solenoid 10'is retained. Field and coil assembly 29 includes a tubular spool 30 of ceramic material which fits tightly around the wall 23 of the tubular inner; housing19. At

either'end of the spool 30 are groups of ferromagnetic laminations 31 and 32 which are closely fitted to the outside diameter of the cylindrical wall 23 10 provide a low loss laminated field structure for the solenoid 10. Lami- I I I I nations 32 are provided with circular apertures 33 which A still further object of this invention is to provide an:

coil 34 is .wound upon the spool 30 with concurrent appli- 3 cations of ceramic potting compound which, when properly cured, add to the original strength of the ceramic spool by imparting to the entire coil structure a rocklike consistency, therebymaking the coil assembly 2% capable of absorbing stresses transmitted from the inner housing19.

Positioned between the laminations 31 and 32 and tightly encircling the spool 30 andthefcoil 34 is a stack of ferro magnetic laminations 35. Laminations 35' fill the space between the coil 34 and the, solenoid body 11, and thereby impart additional strength tothe field and coil assembly 29. e i i 1 The terminal posts16 extend through apertures 36 in the closed endof the solenoid body 11 and are provided with insulating s1eeves37, whichinsulate the posts 16 from the solenoid body 11. Insulating sleeves 37 are retained-between outer washers 38, which are attached to theterminal posts 16, and'a terminal post retaining in assembly 39. V The terminal post retaining assembly 39 is composed of circularceramic insulating retainers 46 which, are tightly compressed between the insulating sleeves 37 and the stack laminations 32. Terminal posts 16 extend through apertures 33 in the lam'inatio'ns 32 and are electrically connected to the coil 34 by leads .16.

In operation, the solenoid of the present invention may be advantageously employed as an actuator mechanating current magnetic circuit, while retaining the structural and mechanical advantages of a slotted construction for the components which are subject to mechanical movement and wear.

The efiiciency of the tubular inner housing 19 is ad- 7 V vanced by the thinness of thewall 23 and the alternate sections 20, 21 and 22 of magnetic and non-magnetic material. 3 r a a i Y s It has been found that the extremely thin Wall 23 of the inner assembly 19 reduces the concentration of eddy current through the inner housing assembly, which represents a short circuitto the core for such eddy currents. netic material, losses would be incurred due to eddy currents generated in the material itself in addition to the further loss incurred due to the flux'short circuit path to the working components inside the inner housing assembly 19. Furthermore, if the wall 23 were composed entirely of non-magneticmaterial, a non-productive nism for valve units utilized within high pressure fluid systems. When used as a valve actuator, the solenoid it) would be connected to a high pressure valve by means of connectors inserted through the apertures 13 ofthe flange 12. The solenoid actuating pin- 14 would extend into the valve casing and would engage the valve mechanism, not shown.- The spring action of-thisvalve mechanism would hold the solenoid plunger 28 in the retracted position'against the'end wall 24 of the inner housing assembly 19, asillustrated by FIGURE 3 until the solenoid coil 34] was energizedriAt this time, the plunger '28 would-.move (toward theistationaiy core. member 15,

thereby actuating the valve mechanism.

With the solenoid actuating pin .14; engaging a valve mechanism 'within a'high pressure fluid system, the wall 23 and the endwall. 24 of the inner housing assembly would be subjected to the pressures existing'within the fluidsystem. The thin wall 23 taken alone is incapable of withstandingeven minimal pressures due to the extreme thinness of this wall. degree of thinness relative to the walls of the body member 11 and the other components of the solenoid 10,; that it must be supported :by an internal form during the machining'operation. However, in the finished solenoid,

' the Wall 23 is rendered capable of withstanding high fluid pressures, for this wall: is reinforced by the spool 39,

the potted coil 34, and the metallic laminations 31, 32

and 35,'as well as by the outer body assembly 11. These close fitting parts serve to back up the inner housing assembly 19"by accepting substantially all of the stress created by internal pressure. "The heavy shoulder 18 and the thick end wall 24 of the inner housing assembly 19 act with the heavy flange 12 and closed end structure of the outer body assembly ,11 to. permit transmission of endwise forces created by internal pressure down through the sidewalls of the body member 11 and into the con-' necting unitswhich hold the entire assembly to an adjacent valve housing. Y s t The solenoidltl is capable of operating eificiently' from a 400 cycle, 115 volt power supply with no inter- The construction of the. inner housing assembly 19, the stationary core 15, and

The com-, 70

mediate rectification stage.

the plunger 28 enable the solenoid 10 to operate with minimum magnetic and eddy currentlosses. bination of the laminated fixed. magnetic, components31,

'32 and 35 together with the slotted plunger 28 and the slotted fixed core member 15 take advantage of the minimum; eddycurrent losses inherent in a laminated alter- The Wall 23 is of suchav the body structure, the remaining endsection being pro v ded with a laterally extending shoulder, saidshoulder be1ng attached to theopen end of said body structure,

gap Would be introduced in the magnetic circuit between the field and coil assembly 29 and the stationary core 15 I and plunger 28.

By constructing the wall 23 from the extremely thin segments 20 and 22 of magnetic material and 21 of non-.

magnetic material, the non-productivegap in the magnetic circuit of the solenoid is greatly minimized, while the losses, which might be incurred, if the walls 23 were entirely of magnetic material, are eliminated. The welds I i I between .the segments 20, 21 and22 permit transition from magnetic to non-magnetic and back to magneticv materialand additionally. eliminate air-gaps in the flux path through the wall23. t

. It will thus be apparent to, those skilled in the-art that occur'toone skilled in the art, are deemed to berwithin the concepts presented herein and within the scope ot'the appended, claims. What is claimedis:

I 1. A-solenoid adapted for use withhigh pressure; sys-l terns, comprising a hollow body. structurehaving an open end and a closed end, aniinner housing assembly includmg a thin, cylindrical sidewall formed by two endgsections of magnetic material integrally connected to a center section of non-magnetic material, althick end wall secured to one of the end sections at the closed end'of whereby, said inner housing assembly is completely onclosed. within-said body structure with said thin, cylindri. cal sidewall being maintained in spaced relationship there-f 'to' andsaid thick end wall in juxtaposition with said closed end thereoffas slotted' coremember secured within said inner housing assembly, saidcore member having an axial bore "extending therethrough, aslottedfplunger provided" within said innerhousing. assembly inaxial, spaced relationship toysaidcore member, said plunger being'rela .tivelymovable between said core member \andth'e thick d endgwall of said inner housing assembly, an: actuating pin connected'to said' plunger and'extending through the bore o fsaid core member, and a field and coil assembly tightly surrounding the exterior ofthe thin, cylindrical wall 'of- I said inner housing assernblyand extending coaxially' thereof between said thin, circular wall and said body 1 Y structure, said field and coilassembly includingafcerarnic spool mounted upon said-thinvwall', an exciting 'coilwound upon said ceramic spool, said exciting coil being encased v in cured ceramic potting compound of rock-like 'consistency, a plurality :of ferromagnetic laminations mounted ateither end of said ceramic spool and tightly encircling 1 and engaging the thin'wall of said innerhousing assembly, and a stackof ferromagnetic laminations'tightlyencasing- If the wall 23 were constructed entirely of magsaid exciting coil and extending between said exciting coil References Cited by the Examiner and said body structure into engagement with the end la ni- UNITED STATES PATENTS natlons, sald spool, exc1t1ng c011, and lamrnations belng formed to cooperate with said body structure in absorbing 2,561,355 7/51 Flsh substantially all of the pressure applied to the interior of 5 2,562,392 7/51 Ray 317-191 said inner housing assembly. 2,629,766 2/53 VPrgO 2. The solenoid structure of claim 1, wherein the thin, 3350563 8/62 ZIPPer 317186 cylindrical sidewall of said inner housing assembly is machined to a thickness of approximately .016 inch. JOHN BURNS Primary Examiner 

1. A SOLENOID ADAPTED FOR USE WITH HIGH PRESSURE SYSTEMS, COMPRISING A HOLLOW BODY STRUCTURE HAVING AN OPEN END AND A CLOSED END, AN INNER HOUSING ASSEMBLY INCLUDING A THIN, CYLINDRICAL SIDEWALL FORMED BY TWO END SECTIONS OF MAGNETIC MATERIAL INTEGRALLY CONNECTED TO A CENTER SECTION OF NON-MAGNETIC MATERIAL, A THICK END WALL SECURED TO ONE OF THE END SECTIONS AT THE CLOSED END OF THE BODY STRUCTURE, THE REMAINING END SECTION BEING PROVIDED WITH A LATERALLY EXTENDING SHOULDER, SAID SHOULDER BEING ATTACHED TO THE OPEN END OF SAID BODY STRUCTURE, WHEREBY SAID INNER HOUSING ASSEMBLY IS COMPLETELY ENCLOSED WITHIN SAID BODY STRUCTURE WITH SAID THIN, CYLINDRICAL SIDEWALL BEING MAINTAINED IN SPACED RELATIONSHIP THERETO AND SAID THICK END WALL IN JUXTAPOSITION WITH SAID CLOSED END THEREOF, A SLOTTED CORE MEMBER SECURED WITHIN SAID INNER HOUSING ASSEMBLY, SAID CORE MEMBER HAVING AN AXIAL BORE EXTENDING THERETHROUGH, A SLOTTED PLUNGER PROVIDED WITHIN SAID INNER HOUSING ASSEMBLY IN AXIAL, SPACED RELATIONSHIP TO SAID CORE MEMBER, SAID PLUNGER BEING RELATIVELY MOVABLE BETWEEN CORE MEMBER AND THE THICK END WALL OF SAID INNER HOUSING ASSEMBLY, AN ACTUATING PIN CONNECTED TO SAID PLUNGER AND EXTENDING THROUGH THE BORE 